The invention relates to a female terminal for electrical current distribution, being provided with electrocution preventing means.
Such a terminal may exist in the shape of a wall plug, of an adaptor for wall plug, of an extension, or of any electrical current distribution device comprising, broadly stated, at least one assembly of at least two female sockets destined to receive as many male parallel pins belonging to an electrical male plug having a predetermined spacing.
In its (published) French patent application No 77 39232, in its (published) certificates of addition based thereon No 78 16340 and 78 34279, and also in its (published) French patent application No 81 01011, the applicant has already described an electrocution preventing electric current plug.
The present invention is broadly directed to an improvement of these devices, and more particularly, to the one described in the last mentioned French patent application.
The female terminal for electrical current distribution as described in the last mentioned French patent application comprises, broadly stated, at least one assembly of at least two female sockets destined to receive as many male parallel pins belonging to a male electrical plug having a predefined spacing, said female sockets extending parallel to a main axis, the terminal further comprising:
a casing made from an insulating material having an anterior mounting plate having at least two through-bores for the male pins; PA1 a contact support facing the anterior wall, destined to support: PA1 at least two primary contacts destined to receive said male pins, each of these primary contacts comprising to that effect two primary contact surfaces assembled in register with each other, extending in the pathway of the male pin so as to tightingly enclose the latter, these surfaces being connected to a first secondary contact surface; PA1 at least two secondary contacts each having, on the one hand, at least one second contact surface and, on the other hand, electrical connecting means at a current outlet, each second secondary contact surface being assembled to be in register with one of said first secondary surfaces of primary contacts and to thus define an assembly of secondary contact surfaces; PA1 an insulating connecting blade positioned between the casing anterior wall and the contact support, adapted to move along said axis while remaining parallel to itself, this blade having at least two connecting members adapted each to come in simultaneous contact with the two contact surfaces of an assembly of secondary contact surfaces when the blade is in a "working" position, the blade further comprising, in register with the primary contact surfaces of each of the primary contacts, a cavity destined to enable the passage of said primary contact surfaces of the whole of the primary contacts which come in register with the cavity and at least two abutment areas mounted partially in register with said through-bores; PA1 elastic means adapted to maintain the blade spaced from its working position until an assembly of male pins are engaged into said sockets.
Such an electrical current distribution terminal is provided with an electrocution-preventing safety means. Indeed, it is not until the male plug is engaged into the terminal female sockets that the male pins, abutting against the abutment areas through-passages, will apply a compressive force against this connecting blade which will become pushed back, against the spring acting as an elastic means in its working position such that said connecting members supported by said blade will come, each, in simultaneous contact with an assembly of secondary contacts mounted into the contact support, thus enabling the passage of electrical current. On the other hand, when other objects, such as nails, are introduced into the sockets, they will abut against the primary contacts and, until a major force in a predetermined direction is applied against the abutment areas, the connecting blade will remain spaced from its working position: the contact will not be established between the secondary contacts assemblies, such that the current will not get through.
It can be understood why such electrical current distribution female terminals are so important, particularly when they are in the shape of wall plugs that can be easily reached by children that would be tempted to engage therein metallic objects.
The present invention is directed to an improvement of the terminal whose structure is above-mentioned.
Indeed, normally, the connecting blade is pushed back from its working position only when a predetermined force in a predetermined direction (normally parallel to the socket axis) is applied onto the abutment areas of the blade. Such a force is normally applied in the suitable direction when there is introduced a male plug in the female terminal. However, the inventor has discovered that in certain occurrences, particularly when there is introduced a cylindrical metallic object whose external diameter approximates the diameter of the plug male pins, the connector blade could be pushed back in its working position, at least on one of its sides, thus establishing an undesirable contact.
Following his research the applicant has noticed that the fact of being able of thus pushing again the connecting blade in its working position was caused by the fact that the above-noted metallic object was in fact sometimes guided if you will towards an abutment area, by the primary contact surfaces, whereas when there was introduced in the subject socket a metallic object of a diameter slightly smaller, the latter was not naturally guided toward the abutment area and that hence, it was required that a voluntary action be applied to push back the connecting blade.
The present invention is directed to an improvement of the above-noted structure thanks to which there may be introduced into female sockets metallic cylindrical objects whose diameter substantially corresponds to that of a male pin, without triggering the connecting blade, and the latter cannot be pushed back toward its working position until there is introduced in the sockets, simultaneously, two cylindrical pins extending parallel to each other and having the required spacing, i.e. a male plug.
The present invention overcomes this technical problem by proposing a female terminal having, generally speaking, a structure similar to the above-captioned one, and characterized in that the blade cavities are radially exteriorly oriented, as well as the primary contact surfaces, whereas each abutment areas comprises, in register with the associated through-bore, a radially exteriorly inclined surface.
Thanks to these devices, when an object is introduced into the through-bore, even if this object is a cylindrical object having a diameter identical to that of the male pins, the latter will scrape against the abutment area and will radially exteriorly slide, in such a way that it cannot bring the connecting blade toward its working position.
To bring the blade toward its working position, there must absolutely be simultaneously introduced pins extending along parallel directions and having the required spread or spacing: the safety of the device is in this fashion considerably increased.